(1) Get a magnet-- if your metal is attracted, there is iron or
stainless steel there (the nickel in nickel-silver is generally not
enough to be attracted in a decisive manner, at least in my
experience)

(2) Get a little bottle of Silver Testing Solution. Mine is "JSP"
brand

–can’t remember where I got it. Clean a test area, put on a tiny
drop

– if it becomes creamy-colored, the metal is silver; if it turns
green, it’s base metal (brass, copper, nickel-silver). Rinse it off
immediately, and DON’T get the testing solution on you. It’s nasty
stuff. I assume that if you tested an intact piece of gold-filled
wire, it would also remain creamy-colored, although its interior
could be another matter.

I assume that if you tested an intact piece of gold-filled
wire, it would also remain creamy-colored, although its interior
could be another matter.

No, if you place a drop of the acid on gold filled wire, you will
get the same reaction you get on a piece of solid gold wire, since
the surface is in fact gold. A drop on the cut end however will
produce a reaction appropriate to the composition of the base metal.
It would probably fizz green, since the base metal most probably
contains copper.

Get a magnet-- if your metal is attracted, there is iron or
stainless steel there

I have an anecdote. I don’t know what it means-- but it happened.

I melted some casting buttons and poured them into water to make
shot. The resulting bits looked oxidized, so I had the brilliant
idea of throwing them into the tumbler. I figured I could just pick
up the steel shot with a magnet and leave the silver. It worked, but
took for-e-ver!! Anyway, a few of the pieces of silver stuck to the
magnet! I removed any that did, but there is no apparent way the
silver could have gotten contaminated with iron or nickel or
anything else. I have no idea why this occurred.

Noel, I have no idea how come you got “magnetic silver”(!) but your
quote from my post–

Get a magnet-- if your metal is attracted, there is iron or >>
stainless steel there

reminded me to correct it, in that stainless steel is not necessarily
magnetic. I tried my magnet on those commercial ear-wires made of
stainless (surgical) steel. They weren’t at all magnetic… I know
some folks have explained that on earlier posts.